To compare the measurements acquired with the linear and convex probe and to assess the intra-observer reproducibility of a two dimensional shear wave elastography (2D-SWE GE) technique.

Material and methods:

We conducted a prospective study that included 70 children (age range: 3–17 years, 37.1% girls, mean body mass index 24.73±7.2 kg/m2). Our study population consisted of obese children (n=35) and a control group: normal weight children without liver disease (n=35). Liver stiffness measurements were performed using 2D-SWE.GE (Logiq E9, GE Healthcare, Chalfont St Giles- UK). For each child one examiner performed 10 liver stiffness measurements with both a linear and a convex probe. To assess the intra-observer reproducibility, we calculated, for each probe, the medians for the first five and the last five measurements, respectively. We then calculated the interclass correlation coefficients (ICCs) for the two medians.

Results

Overall, we found significantly higher measurement values for the linear probe: 7.8±5.1 kPa vs 4.1±0.9 kPa, p=0.001. The measurements were also higher for the linear probe, both in obese and controls: 9.9±6.1 kPa vs 4.2±0.8 kPa, p=0.01 and 6.5±4 kPa vs 3.9±1 kPa, p=0.235. As for the intraobserver reproducibility, we found no differences between the two sets of measurements for both the linear (8.2±5.8 kPa vs 8.1±5.6 kPa, p=0.25) and the convex probe (4.2±0.9 kPa vs 4.3±0.9 kPa, p=0.33). The agreement between measurements was excellent for both probes: ICC=0.956 (95% CI: 0.922–0.975) and ICC=0.927 (95% CI: 0.883–0.955).

Conclusion

Measurements acquired with the linear and convex probe are not superimposable. 2D-SWE GE is a reproducible method for liver stiffness measurements in children.